Muscle cytoskeletal disruption occurs within the first 15 min of cyclic eccentric contraction

Muscle cytoskeletal disruption occurs within the first 15 min of cyclic eccentric contraction
R. L. Lieber , L. E. Thornell , and J. Friden
1996-01-01 00:00:00
STRUCTURAL DAMAGE after forced lengthening ( ) has been reported in a number of different muscles and experimental models (7, 14, 20, 33). Such muscle actions are relatively common normal movement when, for example, the quadriceps are forced to lengthen as the foot strikes the ground. Postexercise degenerative responses reported include fiber necrosis (17), sublethal damage of contractile and components (6, 20>, and of membranous components such as mitochondria that show paracrystalline inclusions (8). Recently, we measured muscle tension cyclic and compared it with the muscle tension measured cyclic passive stretch and isometric (14). We found that the added mechanical tension due to (calculated as the difference between tension and the sum of isometric tension and passive stretch tension; Fig. 1) disappeared -7 min into the MUSCLE 278 0161-7567/96 $5.00 Copyright paradigm. We interpreted this result to indicate that significant mechanical events unique to occurred early in the exercise session. This finding was supported by demonstrating histological abnormalities in muscle fibers with very low oxidative capacity (type fast glycolytic fibers), which would be expected to fatigue early in the treatment period (12). Despite these early mechanical changes, the hypothesis that muscle structural damage occurs within the first few
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Muscle cytoskeletal disruption occurs within the first 15 min of cyclic eccentric contraction

Abstract

STRUCTURAL DAMAGE after forced lengthening ( ) has been reported in a number of different muscles and experimental models (7, 14, 20, 33). Such muscle actions are relatively common normal movement when, for example, the quadriceps are forced to lengthen as the foot strikes the ground. Postexercise degenerative responses reported include fiber necrosis (17), sublethal damage of contractile and components (6, 20>, and of membranous components such as mitochondria that show paracrystalline inclusions (8). Recently, we measured muscle tension cyclic and compared it with the muscle tension measured cyclic passive stretch and isometric (14). We found that the added mechanical tension due to (calculated as the difference between tension and the sum of isometric tension and passive stretch tension; Fig. 1) disappeared -7 min into the MUSCLE 278 0161-7567/96 $5.00 Copyright paradigm. We interpreted this result to indicate that significant mechanical events unique to occurred early in the exercise session. This finding was supported by demonstrating histological abnormalities in muscle fibers with very low oxidative capacity (type fast glycolytic fibers), which would be expected to fatigue early in the treatment period (12). Despite these early mechanical changes, the hypothesis that muscle structural damage occurs within the first few